Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3924929 A
Publication typeGrant
Publication date9 Dec 1975
Filing date6 Mar 1972
Priority date14 Nov 1966
Publication numberUS 3924929 A, US 3924929A, US-A-3924929, US3924929 A, US3924929A
InventorsHolmen Reynold E, Nellessen Alfred H
Original AssigneeMinnesota Mining & Mfg
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Retro-reflective sheet material
US 3924929 A
Images(1)
Previous page
Next page
Description  (OCR text may contain errors)

United States Patent 1191 Holmen et al.

[ Dec. 9, 1975 RETRO-REFLECTIVE SHEET MATERIAL [75] Inventors: Reynold E. Holmen, White Bear Lake; Alfred H. Nellessen, Roseville, both of Minn.

[ 73] Assignee: Minnesota Mining & Manufacturing Company, St. Paul, Minn.

[22] Filed: Mar. 6, 1972 [21] Appl. No.: 232,023

Related U.S. Application Data [63] Continuation of Ser. No. 594,137, Nov. 14, 1966,

abandoned.

[52] U.S. Cl. 350/103; 350/67; 94/15 [51] Int. Cl. G02B 5/12 [58] Field of Search 40/135; 350/67, 97-109; 94/ 1.5

[56] References Cited UNITED STATES PATENTS 322,151 5/1943 Swarovsko 350/103 2,037,773 4/1936 Egnon 40/208 3,140,340 7/1964 Weber 350/103 3,359,671 12/1967 Nier et al. 350/103 FOREIGN PATENTS OR APPLICATIONS 987,243 3/1965 United Kingdom 350/67 547,786 9/1956 Italy 350/101 Primary ExaminerRonald L. Wibert Assistant ExaminerMichael J. Tokar Attorney, Agent, or Firm-Alexander, Sell, Steldt & DeLal-lunt [5 7] ABSTRACT A retro-reflective article having a retro-reflectivity of at least 400 candle power per foot candle per square foot when measured by a detector at an angle of 0.2 degrees divergence from an incident light beam and having a plurality of cube'corner retro-reflecting units and septa embossed on one surface, the septa being disposed to divide said surface into a multiplicity of separate sealable cells with a plurality of units in each cell.

9 Claims, 5 Drawing Figures U.S. Patent Dec. 9, 1975 3,924,929

RETRO-REFLECTIVE SHEET MATERIAL CROSS-REFERENCES TO RELATED APPLICATIONS This application is a continuation of application U.S. Ser. No. 594,137, filed Nov. 14, 1966, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a retro-reflecting sheet material, and in one aspect, to a cellular cube-corner retro-reflecting sheet material affording increased performance over prior known material.

The fundamental characteristic of reflex-reflecting or retro-reflecting material is its ability of returning back a brilliant cone of light toward the source of an angularly incident ray. This is to be distinguished from mirrors which cause specular reflection and from diffuse reflecting surfaces which scatter the incident light in all directions without selective return in the direction of incidence.

It has been conventional practice to form letters on highway signs by applying retro-reflective articles in the form of a multiplicity of unitary circular buttons upon a sign board. The buttons are arranged to block in or outline a letter, or other indicia. These buttons comprise a lens of transparent material, the rear surface of which is embossed with cube-corner retro-reflective units. A metal plate is usually sealed to the edges of the circular lens. These buttons commonly vary in diameter from one-half inch to seven inches (l3mm-l8cm). In arranging circular buttons however, to block in indicia, a large amount of the area to be covered is lost between the buttons with a resulting measurable decrease in brilliance over what might exist if the area were completely covered by such material. Further, when one of these buttons becomes damaged, allowing dirt or moisture to contaminate the cube-corner retroreflective units embossed on the rear surface thereof, the reflective properties of the entire button are soon lost. This further decreases the brilliance and legibility of the sign at night and eventually the sign requires maintenance.

Another commonly employed material is cube-corner sheeting which has a reflective metal coating on the side embossed with cube-corner retro-reflecting units. This coating materially decreases the brilliance of the sheeting and causes the same to appear undesirably dark during daylight hours.

The sheet material of the present invention would materially increase the brilliance of the indicia on a sign by increasing the unit area covered by a cube-corner retro-reflective material. At the same time, the sheet material of this invention is constructed so that far less maintenance on the signs is required. Further, the sheet material of the present invention may be cut to form letter copy, and time and material need not be utilized in edge sealing to protect the cube-corners from contamination by dust or moisture.

The material of this invention has an advantage over the cube-corner material which has the cube-corner rear surface vapor-coated and painted in that the material of this invention offers greater retro-reflective brilliance and does not appear to be dark in color during the daylight hours.

The material of the present invention affords these advantages because the cube-corner prism retroreflecting units in the material have a substantially continuous prism-air interface and the material has a novel multieellular structure. The cells afforded by the present invention are of a size such that the loss of the retro-reflectivity over the area of an occasional entire cell does not cause any significant decrease in total brilliance of a legend formed from our material. The built in cellular structure also permits cutting of the material to form the desired indicia or legends without the added operation of edge sealing.

The brilliant cellular retro-reflective sheet material of the present invention will have a great advantage in the making of signs for streets and highways. The present invention provides a material which will exhibit the high brilliance needed for long-range advance warning to motorists travelling at high speeds along the super highways. Also, this cellular structure provides a longlasting sign in that damage to a sign by vandals striking the same with pop bottles or rifle bullets will be limited to only those cells actually struck and broken by the force and will not involve a significant area of the entire indicia or legend as is the case with prior art unitary cube-corner sheeting or button-like structures.

Each sheet or plate of material constructed in accordance with the present invention includes at least three cells and each cell is polygonal and contains at least three cube-corner retro-reflecting units, whether said units are formed to represent. a cube section formed by a near diagonal cut of a cube or whether they contain three full square side walls of a cube and the included trihedral angle. The cell structure provides an improved material and the area thereof occupied by septa defining said cell should be kept to a minimum since the area so occupied is lost for retro-reflective purposes.

The present invention further provides a retro-reflective sheet material of any desired size from which indicia for signs may be cut. In a preferred embodiment the sheet material of this invention may be rolled or folded even though the cube-corners are embossed on a rigid transparent material. This is accomplished by adhering a multiplicity of mating small separate strips or platelike cube-corner articles in a predetermined close pattern on a flexible backing. The cube-corner articles are preferably aligned to place edges of the same in an axial alignment with respect to the direction the material will be rolled, or they may be aligned such that the same may be folded once along a joint.

These and other novel features and advantages will become more apparent after reading the following detailed description which relates to the accompanying drawing wherein:

FIG. 1 is a rear view of one cube-corner cellular retro-reflecting article formed in accordance with the present invention;

FIG. 2 is a rear view of another article formed in accordance with the present invention;

FIG. 3 is a fragmentary vertical sectional view of a retro-reflecting sheet material formed in accordance with the present invention;

FIG. 4 is an enlarged fragmentary rear view of an article formed in accordance with the present invention having cube-corner retro-reflecting units illustrating a second embodiment; and

FIG. 5 is a perspective view of a small sheet of material formed according to the present invention and partially rolled.

Referring now to the drawing, FIGS. 1 through 3 illustrate two articles generally designated 10 and 10a having different geometric shapes and formed with cells of different shapes in accordance with the present invention. Each article is monolithic and is made from a transparent polymeric solid material, for example polymethylmethacrylate, polystyrene, or celluloseacetate, by the use of suitable pressing or molding techniques known in the art. The articles and 10a have a smooth light receiving front face and the back face (shown in FIGS. 1 and 2) has embossed thereon a multiplicity of trihedral prismatic retro-reflecting units 11 and 11a separated into cells by interconnecting septa. In the preferred embodiment the front face and the free edges of the septa are disposed in parallel planes and the articles have a uniform thickness, although the articles could have curved faces or flat nonparallel faces to make the material less directional. The articles thus each have throughout an area within its perimeter a substantially smooth uninterrupted front face and the back face opposite said area is formed with units 11 and 11a and with intervening septa to form a plurality of cells.

The plate-like article 10 shown in FIG. 1 is trapezoidal in shape and is embossed with contiguous prismatic cube-corner retro-reflecting units 11, each being formed by three smooth planar surfaces meeting in a point and disposed at right angles to each other. Wall members or septa l2 border the plate 10 and are continuous with septa 13 which divide the article 10 into three similar cells, each cell of which includes three cube-corner retro-reflecting units 11. As illustrated, each of these retro-reflecting units is defined by planar surfaces amounting to substantially three complete sides of a cube.

FIG. 2 illustrates another embodiment of an article formed in accordance with the present invention wherein the article 10a is rectangular having septa 12a bordering the article and septa 13a dividing the article into separate rectangular cells also having a rectangular configuration and enclosing within each cell three or more contiguous cube-corner retro-reflecting units 11a. The lead lines on the numerals are directed to the points of the units.

It is desired that the cells be as small in size as possible but yet the reflectivity of an article must, as a practical matter, be sufficient such that the non-retroreflective areas caused by the septa forming a grid and the pattern of polygonal cells on the rear surface of the article do not constitute a greater area-than that defined by retro-reflecting units. Preferably the area of an article occupied by the septa is such that their area compared to the area occupied by retro-reflecting units results in a measure of the retro-reflectivity of at least 400 candle power per square foot (930 square centimeters) of area per foot candle of transmittible incident light measured at 0.2 degrees divergence from a light beam at 4 degrees incidence. The cells should therefore preferably have a retro-reflective area not less than 0.006 square inch (4 square millimeters) or greater than one square inch (6 square centimeters) and should include not less than 3 retro-reflecting units. The units may have a width, measured between centers of opposed edges of facets defining a cube corner retro-reflecting unit, of between about l/25 and inch (1mm and 10mm). The septa should have a free bondable edge surface of at least l/l00 inch (0.2mm) in width and preferably not over /a inch (3mm) and indeed never over A inch (6mm) wide, giving an area on the free edge of the septa sufficient to provide a bonding surface for the article to a backing sheet.

FIG. 3 illustrates a vertical section through an article such as 10a with a backing 16 bonded uninterruptedly to the free edges of the septa 12a and 13a. This backing 16 is preferably a material which is essentially vapor impermeable and durable when exposed to the weather. Examples of such materials for the backing are aluminum sheeting, galvanized steel, various laminates and/or durable polymeric film-like sheet materials suitably formed, for example, of polymethyl methacrylate, polyesters, polyamides, polyvinyl fluoride, polyvinyl chloride, or polychlorotrifluoroethylene. This backing may be flexible or rigid, but it must be hermetically bonded uninterruptedly to all the free edges of the septa providing a multiplicity of hermetically sealed cells which are each free from contamination by dust particles or moisture to maintain a substantially complete prism-air interface on the smooth facets of the retro-reflecting units 1111. There is no silvering or other reflective coating on the units. In fact, such coatings 1 only degrade or diminish the retro-reflectivity of the article.

The free edges of the septa form a grid and may be bonded to the backing by various means such as heat sealing (using a grid next to the backing corresponding to the pattern of the septa); adhesives, either pressure sensitive or heat or solvent activatable adhesives; or by using a solvent which attacks the septa to make the free edge tacky and, preferably, the backing material to thus form a bond. The adhesive may be applied to the face of the backing, to the face edges of the septa or to both. Further, a polymerizable syrup, e.g. methylmethacrylate syrup, could be applied to the backing or septa to bond the articles. It is important, however, to avoid exposure of the facets forming the retro-reflecting units to the solvents, adhesives or excessive heat.

It will be noted in FIG. 3 that the free edge surfaces of septa 12a and 13a are spaced rearwardly from the smooth front surface of the article a distance greater than peaks of the cube-corner reflecting units 11a. such that an air space is formed between the entire retroreflecting unit and the backing. As the size of the retroreflecting units increases beyond the H25 inch (lmm) size it becomes increasingly feasible to limit the rearward extentof the septa such that they terminate in edge surfaces. spaced from the front surface of the article only as far rearward as the rearmost points of the retro-reflecting units. The septa must bespaced at least as far as the rearmost points or the prism-air interface is disturbed by contact of the facets with the backing and when the backing is coated with an adhesive layer some degradation of the retro-reflective effect of the units occurs.

As shown in FIG. 3, for one cell, the voids formed between the article 10a and the backing 16 may, for example, be filled with a particulate material 17 affording a back filling to strengthen the construction of the sheeting without degradation of the retro-reflectivity of the material. The particulate material 17 maintains a substantially continuous prism-air interface with the facets of the cube-corner units because the particles afford substantially only point contact with said facets. Examples of such particulate material are glass bubbles, granules of calcium sulfate and pigments, preferably between 2 to I00 microns in size. The more nearly spherical the particulate, the larger the size of the particulate may be, within this range, without excessive surface contact. The particulate could be fused together, if desired, provided the point contact aforenoted is maintained.

FIG. 4 shows a fragmentary rear view of an article 1017 divided by septa 13b to place sixteen retro-reflecting units 115 within a cell. The units 11b are defined by 3 planar facets forming a point and intersecting each other at right angles. The facets are each less than a complete wall of a' cube but afford good retro-reflection and the groups of four cubec orners afford easy division of the article into cells each having cube-corners in some multiple of four, but the area of the cell should not be greater than 1 square inch (6 square centimeters).

A multiplicity of the articles, such as either 10, 10a or 10b, may be bonded to a flexible backing, such as a polyester or polyvinyl chloride web, affording a large sheet of cellular cube-corner retro-reflecting material from which indicia may be cut for forming a sign. A fragment of such a sheet 22 is illustrated in FIG. 5 with a plurality of articles 10a bonded to a flexible backing web 21. Such sheeting may be rolled with the adhered plate-like articles 10a aligned to permit folds to be formed therein which extend axially of the roll of material. The articles la are placed on the backing in such a manner that when placed on a flat article the edges of each adjacent plate-like article are contiguous to afford substantially complete coverage of the sign board upon which such sheeting may be attached. FIG. illustrates a plurality of rectangular articles such as are illustrated in FIG. 2 or in FIG. 3 positioned in aligned relationship along two adjacent edges of each article, allowing the same to be rolled or folded in either direction. Thus articles such as may be adhered to'a large flexible sheet or the article 10a may be suitably bonded to a rigid backing 16 which in turn may be adhered to a flexible web 21.

Sheeting, a portion of such as is illustrated in FIGS. 2, 3, 4 and 5, may be cut to form letters. This will obviously cause some to be cut and the respective hermetic seals to be broken. The cell size is such however that, even though the retro-reflecting units in a cut cell become contaminated and lose their retro-reflecting property, only small insignificant segments of a sign or legend are lost since the retro-reflective area of a cell preferably is not greater than one square inch (6 square centimeters).

Providing a substantially complete prism-air interface to the retro-reflective unit rather than coating the same with a reflective metal finish increases the efficiency of cube-corner units since all of the reflection of the light is carried on within the transparent material forming the cube-corner prism. Further, sheet material according to the present invention affords an advantage over reflective-coated cube-corner material in that the sheet of this invention does not have a darkened appearance in the daylight. Of course, colored transparent material of either a silver white, red or yellow will maintain its colored appearance satisfactorily in the daylight as well as under the artificial light at night.

Having thus disclosed the present invention by reference to the accompanying drawing, it is to be understood that modifications may be made herein without departing from the spirit or scope of the present invention.

What is claimed is:

l. A cellular reflector structure having a plurality of individual adjacent cells for providing improved vandal-resistant reflectors, signs and legends having high retroreflectivity and good'daytime color appearance, said reflector structure comprising a monolithic body of transparent material having a light receiving from face having a smooth uninterrupted surface area extending over adjacent cells and i a rear face having a rear surface area immediately opposite and coextensive with said uninterrupted front surface area, said rear surface area having a plurality of intersecting septa visible from said front face defining and isolating a plurality of polygonal cells each from the other and having a plurality of cube-corner retroreflecting units each having a set of three mutually perpendicular facets, each said cell having an area not greater than about one square inch and containing at least three of said cube-corner retroreflecting units and the combined area within said cells being not less than the combined area of said septa, said septa having 1 continuous free edges positioned rearward of the front face at least as far as said cube-corner retroreflecting units, which free edges permit the structure to be affixed to a backing to hermetically seal the cells individually,

said cube-corner retroreflecting units being oriented in said cells to reflect light falling upon them through said front face back toward the source thereof to render said reflector structure highly visible at night and said septa improving the day time appearance of the structure.

2. A reflector structure according to claim 1 wherein a backing is hermetically bonded uninterruptedly to all the free edges of said septa to form a plurality of hermetically sealed cellsenclosing said cube-corner retroreflecting units.

3. A reflector structure according to claim 1 wherein the hermetically sealed cells contain a particulate material of a size to afford substantially only point contact with the facets defining said cube-corner retro-reflecting units.

4. A cellular reflector structure having a plurality of individual adjacent cells for providing improved vandal-resistant reflectors, signs and legends having high retro-reflectivity and good daytime color appearance, said reflector structure comprising a monolithic body of transparent material having a light receiving front face having a smooth uninter rupted surface area extending over adjacent cells and a rear face having a rear surface area immediately opposite and coextensive with said uninterrupted front surface area, said rear surface area having a plurality of intersecting septa visible from said front face defining and isolating a plurality of polygonal cells each from the other and having a plurality of cube-corner retroreflecting units each having a set of three mutually perpendicular facets, each said cell having an area not greater than about one square inch and containing at least three of said cube-corner retroreflecting units and the combined area within said cells being not less than the combined area of said septa such that the retroreflectivity of said body is at least 400 candle power per square foot of area per foot candle of transmittable incident light, said septa having continuous free edges positioned rear-ward of the front face at least as far as said cube-corner retroreflecting units, which free edges permit the structure to be affixed to a backing to hermetically seal the cells individually,

said cube-corner retroreflecting units being oriented in said cells to reflect light falling upon them through said front face back toward the source thereof to render said reflector structure highly visible at night and said septa improving the day time appearance of the structure.

5. A retro-reflective article according to claim 4 wherein said article is of uniform thickness with said front surface smooth and planar, and with said free edges of said septa disposed in a plane parallel to said front face.

6. A retroreflective sheet material having a plurality of individual adjacent cells for providing improved vandal-resistant reflectors, signs and legends having high retroreflectivity and good daytime color appearance, said sheet material comprising a monolithic article of transparent material having a light receiving front face having a smooth uninterrupted surface area extending over adjacent cells and a rear face having a rear surface area immediately opposite and coextensive with said uninterrupted front surface area, said rear surface area having a plurality of intersecting septa visible from said front face defining and isolating a plurality of polygonal cells each from the other and having a plurality of cube-corner,retroreflecting units each having a set of three mutually perpendicular facets, each said cell having an area not greater than about one square inch and containing at least three of said cube-corner retroreflecting units and the combined area within said cells being not less than the combined area of said septa, said septa having continuous free edges positioned rearward of the front face at least as far as said cube-corner retroflecting units, which free edges permit the structure to be affixed to a backing to hermetically seal the cells individually, said cube-corner retroflecting units being oriented in said cells to reflect light falling upon them through said front face back toward the source thereof to render said reflector structure highly visible at night and said septa improving the daytime appearance of the structure, and

a backing hermetically bonded uninterruptedly to all the free edges of said septa of said monolithic article to form hermetically sealed cells enclosing said cube-corner units.

7. A retro-reflective sheet material according to claim 6 wherein said article is plate-like having a uniform thickness with said front surface being planar and with said cells having a uniform .size.

8. A retro-reflective sheet material according to claim 6 wherein said sheet material comprises a plurality of said retro-reflective articles positioned in contiguous relationship, and wherein said articles are joined by a flexible material permitting the sheet material to be rolled or folded.

9. A retro-reflective sheet material according to claim 6 wherein the hermetically sealed cells contain a particulate material of a size to afford substantially only point contact with the facets defining said cube-corner retro-reflecting units.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US322151 *17 Feb 188514 Jul 1885 beaumont
US2037773 *18 Nov 193221 Apr 1936Eynon Benjamin GMotor vehicle registration marker
US3140340 *1 Mar 19617 Jul 1964Minnesota Mining & MfgReflex reflector article
US3359671 *25 Apr 196326 Dec 1967Nier Erich-ArthurSignboard, more particularly traffic sign
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4025159 *17 Feb 197624 May 1977Minnesota Mining And Manufacturing CompanyCellular retroreflective sheeting
US4070095 *2 Feb 197624 Jan 1978Itl Industries, Inc.Pavement marker and reflector assembly
US4208090 *22 Dec 197617 Jun 1980Amerace CorporationReflector structure
US4224002 *4 Aug 197823 Sep 1980Amerace CorporationHighway delineator
US4243618 *23 Oct 19786 Jan 1981Avery International CorporationMethod for forming retroreflective sheeting
US4498733 *2 Jul 198212 Feb 1985Amerace CorporationReflector structure
US4555161 *16 Feb 198426 Nov 1985Reflexite CorporationEncapsulated retroreflective material and method of making same
US4618518 *20 Jun 198521 Oct 1986Amerace CorporationHighway and street signs
US4681402 *2 Oct 198521 Jul 1987Tiffany Carlton RRainbow projector
US4703999 *16 Jun 19863 Nov 1987Minnesota Mining And Manufacturing CompanyWide-angle-reflective cube-corner retroreflective sheeting
US4875798 *30 Jun 198824 Oct 1989Minnesota Mining And Manufacturing CompanyRetroreflective pavement marker
US4921319 *23 Jan 19891 May 1990American Bank Note Holographics, Inc.Surface relief hologram structure with reflection from an air interface
US4952023 *18 Mar 198828 Aug 1990Minnesota Mining And Manufacturing CompanyInternally illuminated retroreflective sign
US5069964 *22 Feb 19913 Dec 1991Minnesota Mining And Manufacturing CompanyFlexible, substrate-insular retroreflective sheeting
US5122902 *31 Mar 198916 Jun 1992Minnesota Mining And Manufacturing CompanyRetroreflective articles having light-transmissive surfaces
US5138488 *10 Sep 199011 Aug 1992Minnesota Mining And Manufacturing CompanyRetroreflective material with improved angularity
US5189553 *8 Jun 199223 Feb 1993Minnesota Mining And Manufacturing CompanyOptimized construction of retroreflective articles for curved applications
US5229882 *16 May 199020 Jul 1993Reflexite CorporationColored retroreflective sheeting and method of making same
US5264063 *16 May 199023 Nov 1993Reflexite CorporationCoating resin sheet with reflective microprisms
US5450235 *20 Oct 199312 Sep 1995Minnesota Mining And Manufacturing CompanyFlexible cube-corner retroreflective sheeting
US5557836 *20 Oct 199424 Sep 1996Minnesota Mining And Manufacturing CompanyMethod of manufacturing a cube corner article
US5564870 *20 Oct 199415 Oct 1996Minnesota Mining And Manufacturing CompanyMethod of manufacturing an asymmetric cube corner article
US5585164 *20 Oct 199317 Dec 1996Minnesota Mining And Manufacturing CompanyDual groove set retroreflective cube corner article and method of manufacture
US5600484 *20 Oct 19934 Feb 1997Minnesota Mining And Manufacturing CompanyMachining techniques for retroreflective cube corner article and method of manufacture
US5614286 *20 Oct 199325 Mar 1997Minnesota Mining And Manufacturing CompanyConformable cube corner retroreflective sheeting
US5632946 *7 Jun 199527 May 1997Minnesota Mining And Manufacturing CompanyMethods of making a conformable cube corner retroreflective sheeting
US5657162 *26 Jul 199512 Aug 1997Reflexite CorporationRetroreflective articles with multiple size prisms in multiple locations
US5667335 *19 May 199516 Sep 1997Minnesota Mining And Manufacturing CommpanyFreestanding composite forms comprising an isotropic polymeric blends having fibers and fillers; flexibility, impact strength, durability
US5677050 *19 May 199514 Oct 1997Minnesota Mining And Manufacturing CompanyRetroreflective sheeting having an abrasion resistant ceramer coating
US5691846 *7 Jun 199525 Nov 1997Minnesota Mining And Manufacturing CompanyUltra-flexible retroreflective cube corner composite sheetings and methods of manufacture
US5696627 *20 Oct 19949 Dec 1997Minnesota Mining And Manufacturing CompanyDirectly machined raised structure retroreflective cube corner article and method of manufacture
US5706132 *19 Jan 19966 Jan 1998Minnesota Mining And Manufacturing CompanyDual orientation retroreflective sheeting
US5721640 *19 Apr 199624 Feb 1998Minnesota Mining And Manufacturing CompanyMultiple structure cube corner article and method of manufacture
US5734501 *1 Nov 199631 Mar 1998Minnesota Mining And Manufacturing CompanyHighly canted retroreflective cube corner article
US5754338 *8 Nov 199619 May 1998Minnesota Mining And Manufacturing CompanyStructured retroreflective sheeting having a rivet-like connection
US5759468 *3 Oct 19962 Jun 1998Minnesota Mining And Manufacturing CompanyRaised zone retroreflective cube corner article and method of manufacture
US5763049 *30 Apr 19969 Jun 1998Minnesota Mining And Manufacturing CompanyFormed ultra-flexible retroreflective cube-corner composite sheeting with target optical properties and method for making same
US5764413 *6 Jun 19969 Jun 1998Minnesota Mining And Manufacturing CompanyTiled retroreflective sheeting
US5770124 *30 Apr 199623 Jun 1998Minnesota Mining And Manufacturing CompanyMethod of making glittering cube-corner retroreflective sheeting
US5784197 *1 Apr 199621 Jul 1998Minnesota Mining And Manufacturing CompanyUltra-flexible retroreflective sheeting with coated back surface
US5812315 *6 Jun 199622 Sep 1998Minnesota Mining And Manufacturing CompanyCube corner articles exhibiting improved entrance angularity in one or more planes
US5814355 *30 Apr 199629 Sep 1998Minnesota Mining And Manufacturing CompanyIntersecting grooves
US5822121 *6 Jun 199613 Oct 1998Minnesota Mining And Manufacturing CompanyRetroreflective cube corner article having scalene base triangles
US5831767 *6 Jun 19963 Nov 1998Minnesota Mining And Manufacturing CompanyAsymmetric cube corner article
US5840405 *30 Apr 199624 Nov 1998Minnesota Mining And Manufacturing CompanyGlittering cube-corner retroreflective sheeting
US5910858 *1 Apr 19968 Jun 1999Minnesota Mining And Manufacturing CompanyRetroreflective sheeting with coated back surface
US5914812 *8 Aug 199722 Jun 1999Minnesota Mining And Manufacturing CompanyDirectly machined raised structure retroreflective cube corner article and method of manufacture
US5914813 *13 Nov 199722 Jun 19993M Innovative Properties CompanyMultiple structure cube corner article
US5926314 *17 Jul 199820 Jul 1999Minnesota Mining And Manufacturing CompanyRetroreflective cube corner article having scalene base triangles
US5930041 *24 Jul 199827 Jul 1999Stimsonite CorporationMethod of producing cellular retroreflective sheeting
US5936770 *2 Jul 199710 Aug 19993M Innovative Properties CompanyDual orientation retroreflective sheeting
US5946134 *22 Sep 199731 Aug 1999Minnesota Mining & Manufacturing CompanyRaised structure retroreflective article
US5959774 *19 Jan 199928 Sep 19993M Innovative Properties CompanyRaised structure retroreflective article
US5962108 *2 May 19955 Oct 1999Minnesota Mining And Manufacturing CompanyRetroreflective polymer coated flexible fabric material and method of manufacture
US5988820 *14 Mar 199723 Nov 19993M Innovative Properties CompanyFlexible cube-corner retroreflective sheeting
US6021559 *1 Nov 19968 Feb 20003M Innovative Properties CompanyMethods of making a cube corner article master mold
US6080340 *24 Sep 199627 Jun 20003M Innovative Properties CompanyDirectly machining groove sets into a substrate to form an array having a multiple geometric structures including cube corner elements, machining two of groove sets along same path in the substrate but at different depth of grooves
US6126360 *26 Nov 19963 Oct 20003M Innovative Properties CompanyRaised retroreflective pavement marker
US6132861 *4 May 199817 Oct 20003M Innovatives Properties CompanyRetroreflective articles including a cured ceramer composite coating having a combination of excellent abrasion, dew and stain resistant characteristics
US6136416 *11 May 199824 Oct 20003M Innovative Properties CompanyRaised zone retroreflective cube corner article
US6139158 *12 Aug 199731 Oct 2000Reflexite CorporationRetroreflective articles with multiple size prisms in multiple locations
US6166856 *15 Jun 199826 Dec 20003M Innovative Properties CompanySelf light-emitting retroreflective sheet and method for producing the same
US616827521 Oct 19992 Jan 20013M Innovative Properties CompanyRetroreflective cube corner article
US622479213 Apr 19991 May 20013M Innovative Properties CompanyCutting and edge sealing cellular retroreflective sheeting
US62458333 Sep 199912 Jun 20013M Innovative PropertiesColloidal oxide in binder
US6253477 *23 Sep 19983 Jul 2001Hallmark Technologies, Inc.Retro-reflective sign
US62650613 Sep 199924 Jul 20013M Innovative Properties CompanyFree radical curable binder, inorganic oxide, and hydrolyzable fluorinated silane
US627747028 Dec 199921 Aug 20013M Innovative Properties CompanyMethod of forming cube corner geometric structures in a substrate using both replicating and machining processes
US631886724 May 200020 Nov 20013M Innovative Properties CompanyConformable cube corner retroreflective sheeting
US635003516 Aug 199526 Feb 20023M Innovative Properties CompanyFlexible cube-corner retroreflective sheeting
US63527584 May 19985 Mar 20023M Innovative Properties CompanyPatterned films or coatings that are capable of being made in a single coating step from the same composition.
US63765768 Dec 200023 Apr 20023M Innovative Properties CompanyCeramer composition incorporating fluoro/silane component and having abrasion and stain resistant characteristics
US641361515 Jun 20012 Jul 20023M Innovative Properties CompanyCube corner geometric structures in a substrate formed by both replicating and machining processes
US647061029 May 199829 Oct 20023M Innovative Properties CompanyPrefabricated retroreflective sign
US650855930 Jul 200121 Jan 20033M Innovative Properties CompanySegments comprising multilayer thermoplastic resins having grid patterns and gaps filled with curable acrylated resins; protective devices or signs; efficiency
US664533111 Sep 200211 Nov 20033M Innovative Properties CompanyPrefabricated retroreflective sign
US665630724 Nov 19992 Dec 20033M Innovative Properties CompanyMethod of making signs having metalized cube corner sheeting
US687786619 Aug 200212 Apr 2005Reflexite CorporationMulti-orientation retroreflective structure
US695817918 Dec 200025 Oct 20053M Innovative Properties CompanySegmented sheeting and methods of making and using same
US702584726 Jun 200311 Apr 20063M Innovative Properties CompanySegmented sheeting and methods of making and using same
US71859934 Jan 20026 Mar 20073M Innovative Properties CompanyFlexible cube-corner retroflective sheeting
US72510794 Jan 200631 Jul 2007General Electric CompanyBrightness enhancement film, and methods of making and using the same
US734178410 Sep 200411 Mar 2008General Electric CompanyLight management film and its preparation and use
US738416126 Mar 200710 Jun 20083M Innovative Properties CompanyStructured surface articles containing geometric structures with compound faces and methods for making same
US756132317 Jun 200514 Jul 2009Idc, LlcOptical films for directing light towards active areas of displays
US756299131 Oct 200721 Jul 20093M Innovative Properties CompanyStructured surface articles containing geometric structures with compound faces and methods for making same
US756880720 Sep 20064 Aug 20093M Innovative Properties CompanyFlexible cube-corner retroreflective sheeting
US760300117 Feb 200613 Oct 2009Qualcomm Mems Technologies, Inc.Method and apparatus for providing back-lighting in an interferometric modulator display device
US77060505 Mar 200427 Apr 2010Qualcomm Mems Technologies, Inc.Integrated modulator illumination
US771290422 Jul 200811 May 20103M Innovative Properties CompanyStructured surface articles containing geometric structures with compound faces and methods for making same
US771974725 Feb 200818 May 2010Qualcomm Mems Technologies, Inc.Method and post structures for interferometric modulation
US773343930 Apr 20078 Jun 2010Qualcomm Mems Technologies, Inc.Dual film light guide for illuminating displays
US775088622 Jul 20056 Jul 2010Qualcomm Mems Technologies, Inc.Methods and devices for lighting displays
US776649821 Jun 20063 Aug 2010Qualcomm Mems Technologies, Inc.Linear solid state illuminator
US777795430 Jan 200717 Aug 2010Qualcomm Mems Technologies, Inc.Systems and methods of providing a light guiding layer
US784584128 Aug 20067 Dec 2010Qualcomm Mems Technologies, Inc.Angle sweeping holographic illuminator
US78558276 Oct 200621 Dec 2010Qualcomm Mems Technologies, Inc.Internal optical isolation structure for integrated front or back lighting
US786439527 Oct 20064 Jan 2011Qualcomm Mems Technologies, Inc.Light guide including optical scattering elements and a method of manufacture
US78809543 May 20061 Feb 2011Qualcomm Mems Technologies, Inc.Integrated modulator illumination
US790731912 May 200615 Mar 2011Qualcomm Mems Technologies, Inc.Method and device for modulating light with optical compensation
US79492137 Dec 200724 May 2011Qualcomm Mems Technologies, Inc.Light illumination of displays with front light guide and coupling elements
US80156203 Sep 200913 Sep 20113M Innovative Properties CompanyVapor permeable retroreflective garment
US804058825 Feb 200818 Oct 2011Qualcomm Mems Technologies, Inc.System and method of illuminating interferometric modulators using backlighting
US804058911 Feb 200918 Oct 2011Qualcomm Mems Technologies, Inc.Devices and methods for enhancing brightness of displays using angle conversion layers
US804995114 Apr 20091 Nov 2011Qualcomm Mems Technologies, Inc.Light with bi-directional propagation
US80618821 Apr 200922 Nov 2011Qualcomm Mems Technologies, Inc.Illumination device with built-in light coupler
US81071556 Oct 200631 Jan 2012Qualcomm Mems Technologies, Inc.System and method for reducing visual artifacts in displays
US81724176 Mar 20098 May 2012Qualcomm Mems Technologies, Inc.Shaped frontlight reflector for use with display
US82241892 Feb 200717 Jul 2012Sunlight Photonics Inc.Retro-directive target for free-space optical communication and method of producing the same
US825602515 Aug 20114 Sep 20123M Innovative Properties CompanyVapor permeable retroreflective garment
US8375933 *23 Jan 200919 Feb 2013Blaine E. MyersSystem and method for heat energy conservation via corner reflectors
US839448528 Feb 201112 Mar 20133M Innovative Properties CompanyCompound mold and structured surface articles containing geometric structures with compound faces and method of making same
US8456649 *3 Sep 20094 Jun 2013Brainlab AgRetro-reflector for image-guided operation systems
US848567226 Mar 201016 Jul 20133M Innovative Properties CompanyStructured surface articles containing geometric structures with compound faces and methods for making same
US85118398 Dec 200920 Aug 2013Nippon Carbide Industries Co., Inc.Retroreflective article
US851184010 May 201020 Aug 2013Nippon Carbide Industries Co., Inc.Hexagonal cube corner retroreflective article
US853484915 Apr 201017 Sep 20133M Innovative Properties CompanyRetroreflecting optical construction
US8591076 *2 Mar 201226 Nov 2013Osram Sylvania Inc.Phosphor sheet having tunable color temperature
US865406123 Dec 200818 Feb 2014Qualcomm Mems Technologies, Inc.Integrated front light solution
US867017118 Oct 201011 Mar 2014Qualcomm Mems Technologies, Inc.Display having an embedded microlens array
US872861025 Feb 200020 May 20143M Innovative Properties CompanyCompound mold and structured surface articles containing geometric structures with compound faces and method of making same
US879842522 Nov 20115 Aug 2014Qualcomm Mems Technologies, Inc.Decoupled holographic film and diffuser
US20100053639 *3 Sep 20094 Mar 2010Christian MaierRetro-reflector for image-guided operation systems
US20130229784 *2 Mar 20125 Sep 2013Osram Sylvania Inc.Phosphor Sheet Having Tunable Color Temperature
CN101960203B23 Jan 20097 Aug 2013布莱恩E迈克尔System and method for heat energy conservation via corner reflectors
EP0142250A2 *19 Sep 198422 May 1985Amerace CorporationRetroreflective sheeting and methods for making same
EP0175031A1 *30 Nov 198426 Mar 1986Amerace CorporationRetroreflective sheeting
EP0342958A217 May 198923 Nov 1989Minnesota Mining And Manufacturing CompanyHigh efficiency cube-corner retroreflective material
EP0349323A2 *29 Jun 19893 Jan 1990Minnesota Mining And Manufacturing CompanyRetroreflective pavement marker
EP0724734A1 *20 Oct 19947 Aug 1996Minnesota Mining And Manufacturing CompanyConformable cube corner retroreflective sheeting
EP0951383A1 *22 May 199727 Oct 1999Stimsonite CorporationRetroreflective articles having microcubes, and tools and methods for forming microcubes
WO2008045363A2 *5 Oct 200717 Apr 2008Qualcomm Mems Technologies IncLight bar with reflector
WO2010067583A18 Dec 200917 Jun 2010Nippon Carbide Industries Co., Inc.Retroreflective article
WO2010131630A110 May 201018 Nov 2010Nippon Carbide Industries Co., Inc.Hexagonal corner cube retroreflective article
WO2012057295A127 Oct 20113 May 2012Nippon Carbide Industries Co., Inc.Cube-cornered retroreflective sheet
Classifications
U.S. Classification359/514, 404/9, 359/532, 40/612, 428/30
International ClassificationG09F13/16, G09F13/04, G02B5/12, G02B5/124
Cooperative ClassificationG09F13/16, G02B5/124, G09F2013/0472
European ClassificationG09F13/16, G02B5/124
Legal Events
DateCodeEventDescription
6 Aug 1990ASAssignment
Owner name: MANUFACTURERS HANOVER TRUST COMPANY, NEW YORK
Free format text: SECURITY INTEREST;ASSIGNOR:AMERACE CORPORATION;REEL/FRAME:005465/0013
Effective date: 19900731